Unsaturated hydrocarbons by oxidative dehydrogenation over catalysts comprising nickel and iron



United States Patent 6 3,303,236 UNSATURATED HYDROCARBONS BY OXIDA- TIVEDEHYDROGENATION OVER CATA- LYSTS C(BMPRISING NICKEL AND IRON Louis J.Croce, East Brunswick, and Laimonis Bajars,

Princeton, N.J., assiguors to Petra-Tex Chemical Corporation, Houston,Tex., a corporation of Delaware No Drawing. Filed Jan. 2, 1964, Ser. No.335,364 17 Claims. (Cl. 260-680) This invention relates to a process fordehydrogenating organic compounds and relates more particularly to thedehydrogenation of hydrocarbons at elevated temperatures in the presenceof oxygen and a particular catalyst.

We have now discovered that greatly improved yields and highselectivities of unsaturated hydrocarbons are obtained bydehydrogenating under certain specified conditons hydrocarbons in thevapor phase at elevated temperatures in the presence of oxygen and acatalyst containing nickel ferrite.

Nickel ferrite is a known commercial product which has uses such as inthe formulation of coatings suitable for high temperature applications.One method for the production of nickel ferrite is by the addition ofnickelous oxide to an aqueous slurry of yellow iron oxide hydrate withthe reaction mixture containing a small amount of the hydrate ofpotassium chloride as a catalyst. This reaction composition is uniformlymixed and then heated at a relatively low temperature above 100 C. for aperiod of several hours. The composition is then reacted for about 30minutes at a temperature of 900 C. The reaction product is then groundand pelleted into catalyst particles.

Hydrocarbons to be dehydrogenated according to the process of thisinvention are hydrocarbons of 4 to 7 carbon atoms and preferably arealiphatic hydrocarbons selected from the group consisting of saturatedhydrocarbons, monoolefins, diolefins and mixtures thereof of 4 to 5 or 6carbon atoms having a straight chain of at least four carbon atoms andcycloaliphatics. Examples of preferred feed materials are butene-l,cis-butene-2, transbutene-2, Z-methylbutene-l, 2-methylbutene-2,2-methylbutene-3, nbutane, buta-diene-LZ, methyl lbutane,2-methylpentene-l, cyclohexene, 2-methylpentene-2 and mixtures thereof.For example, n'butane may be converted to a mixture of butene-l andbutene-Z or may be converted to a mixture of butene-l, b-utene-Z and/orbutadiene-1,3. A mixture of n-butane and butene-2 may be converted tobutadiene-1,3 or to a mixture of butadiene-l,3 together with somebutene-2 and butene-l. Vinyl acetylene may be present at a product,particularly when butadiene-1,3 is used as a feedstock. Thus, theprocess of this invention is useful in converting hydrocarbons to lesssaturated hydrocarbons of the same number of carbon atoms. The majorproportion of the hydrocarbon converted will be to less saturatedhydrocarbons of the same number of carbon atoms. Particularly thepreferred products are butadiene-l,3 and isoprene. Useful feeds may bemixed hydrocarbon streams such as refinery streams, or the olefincontaining hydrocarbon mixture obtained as the product from thedehydrogenation of hydrocarbons. In the production of gasoline fromhigher hydrocarbons by either thermal or catalytic cracking ahydrocarbon stream containing predominantly hydrocarbons of 4 carbonatoms may be produced and may comprise a mixture of butenes 3,303,230Patented Feb. 7, 1967 together with butadiene, butane, isobutane,isobutylene and other ingredients in minor amounts. These and otherrefinery by-products which contain normal, ethylenically unsaturatedhydrocarbons are useful as starting materials. Although various mixturesof hydrocarbons are useful, the preferred hydrocarbon feed contains atleast 50 Weight percent of a hydrocarbon selected from the groupconsisting of butene-l, butene-2, n-butane, butadiene-l,3,Z-methylbutene-l, Z-methylbutene-Z, Z-methylb-utene-3 and mixturesthereof, and more preferably con tains at least weight percent of one ormore of these hydrocarbons (with both of these percentages being basedon the total weight of the organic composition of the feed to thereactor). Any remainder may be, for ex ample, essentially aliphatichydrocarbons. This invention is particularly useful to provide a processwhereby the major product of the hydrocarbon converted is adehydrogenated hydrocarbon product having the same num ber of carbonatoms as the hydrocarbon fed.

Oxygen will be present in the reaction zone in an amount within therange of 0.2 to 2.5 mols of oxygen per mol of hydrocarbon to bedehydrogenated. Generally, better reuslts may be obtained if the oxygenconcentration is maintained between about 0.25 and about 1.6 mols ofoxygen per mol of hydrocarbon to be dehydrogenated, such as between 0.35and 1.2 mols of oxygen. The oxygen may be fed to the reactor as pureoxygen, as air, as oxygen-enriched air, oxygen mixed with diluents andso forth. Based on the total gaseous mixture entering the reactor, theoxygen ordinarily will be present in an amount from about 0.5 to 25volume percent of the total gaseous mixture, and more usually will bepresent in an amount from about 1 to 15 volume percent of the total. Thetotal amount of oxygen utilized may be introduced into the gaseousmixture entering the catalytic zone or sometimes it has been founddesirable to add the oxygen in increments, such as to different sectionsof the reactor. The above described proportions of oxygen employed arebased on the total amount of oxygen used. The oxygen may be addeddirectly to the reactor or it may be premixed, for example, with adiluent or steam.

The temperature for the dehydrogenation reaction will be greater than250 C., such as greater than about 300 C. or 375 C., and the maximumtemperature in the reactor may be about 650 C. or 750 C. or perhapshigher under certain circumstances. However, excellent results areobtained within the range of or about 300 C. to 575 C. such as from orabout 325 C. to or about 525 C. The temperatures are measured at themaximum temperature in the reactor. An advantage of this invention isthat lower temperatures of dehydrogenation may be utilized than arepossible in conventional dehydrogenation processes. Another advantage isthat large quantities of heat do not have to be added to the reaction aswas previously required.

The dehydrogenation reaction may be carried out at atmospheric pressure,superatmospheric pressure or at subatmospheric pressure. The totalpressure of the system will normally be about or in excess ofatmospheric pressure, although sub-atomspheric pressure may alsodesiralbly be used. Generally, the total pressure will be between about4 p.s.i.a. and about or p.s.i.a. Preferably the total pressure will beless than about 75 p.s.i.a. and excellent results are obtained at aboutatmospheric pressure.

The initial partial pressure of the hydrocarbon to be dehydrogenatedwill be equivalent to less than one-half atmosphere at a total pressureof one atmosphere. Generally the combined partial pressure of thehydrocarbon to be dehydrogenated together with the oxygen will also beequivalent to less than one-half atmosphere at a total pressure of oneatmosphere. Preferably, the initial partial pressure of the hydrocarbonto be dehydrogenated will be equivalent to no greater than one-thirdatmosphere or no greater than one-fifth atmosphere at a total pressureof one atmosphere. Also, preferably, the initial partial pressure of thecombined hydrocarbon to be dehydrogenated plus the oxygen will beequivalent to no greater than one-third or no greater than one-fifthatmosphere at a total pressure of one atmosphere. Reference to theinitial partial pressure of the hydrocarbon to be dehydrogenated meansthe partial pressure of the hydrocarbon as it first contacts thecatalytic particles. An equivalent partial pressure at a total pressureof one atmosphere means that one atmosphere total pressure is areference point and does not imply that the total pressure of thereaction must be operated at atmospheric pressure. For example, in amixture of one mol of butene, three rnols of steam, and one mol ofoxygen under a total pressure of one atmosphere, the butene would havean absolute pressure of onefifth of the total pressure, or roughly sixinches of mercury absolute pressure. Equivalent to this six inches ofmercury butene absolute pressure at atmospheric pressure would be butenemixed with oxygen under a vacuum such that the partial pressure of thebutene is 6 inches of mercury absolute. The combination of a diluentsuch as nitrogen, together with the use of a vacuum may be utilized toachieve the desired partial pressure of the hydrocarbon. For the purposeof this invention, also equivalent to the six inches of mercury buteneabsolute pressure at atmoshperic pressure would be the same mixture ofone mol of butene, three rnols of steam and one mol of oxygen under atotal pressure greater than atmospheric, for example, a total pressureof p.s.i.a. Thus, when the total pressure in the reaction zone isgreater than one atmosphere, the absolute values for the pressure of thehydrocarbon to be dehydrogenated will be increased in direct proportionto the increase in total pressure above one atmosphere.

The partial pressures described above may be maintained by the use ofdiluents such as nitrogen, helium or other gases. Conveniently, theoxygen may be added as air with the nitrogen acting as a diluent for thesystem. Mixtures of diluents may be employed. Volatile compounds whichare not dehydrogenated or which are dehydrog-enated only to a limitedextent may be present as diluents.

Preferably the reaction mixture contains a quantity of steam, with therange generally being between about 2 and 40 mols of steam per mol ofhydrocarbon to be dehydrogenated. Preferably steam will be present in anamount from about 3 to 35 mols per mol of hydrocarbon to bedehydrogenated and excellent results have been obtained within the rangeof about 5 to about 30 111015 of steam per mol of hydrocarbon to bedehydrogenated. The functions of the steam are several-fold, and thesteam does not merely act as a diluent. Diluents generally may be usedin the same quantities as specified for the steam. Excellent results areobtained when the gaseous composition fed to the reactor consistsessentially of hydrocarbons, inert diluents and oxygen as the soleoxidizing agent.

The gaseous reactants may be conducted through the reaction chamber at afairly wide range of flow rates. The optimum flow rate will be dependentupon such variables as the temperature of reaction, pressure, particlesize, and whether a fluid bed or fixed bed reactor is utilized.Desirable fiow rates may be established by one skilled in the art.Generally, the flow rates will be within the range of about 0.10 toliquid volumes of the hydrocarbon to be dehydrogeanted per volume ofreactor containing catalyst per hour (referred to as LHSV), wherein thevolumes of hydrocarbon are calculated at standard conditions of 25 C.and 760 mm. of mercury. Usually, the LHSV will be between 0.15 and about5 or 10. For calculation, the volume of reactor containing catalyst isthat volume of reactor space excluding the volume displaced by thecatalyst. For example, if a reactor has a particular volume of cubicfeet of void space, when that void space is filled with catalystparticles, the original void space is the volume of reactor containingcatalyst for the purpose of calculating the How rate. The gaseous hourlyspace velocity (GHSV) is the volume of the hydrocarbon to bedehydrogenated in the form of vapor calculated under standard conditionsof 25 C. and 760 mm. of mercury per volume of reactor space containingcatalyst per hour. Generally, the GI-ISV will be between about 25 and6400, and excellent results have been between about 38 and 3800.Suitable contact times are, for example, from about 0.001 or higher toabout 5 or 10 seconds, with particularly good results being obtainedbetween 0.01 and 3 seconds. The contact time is the cal- .culated dwelltime of the reaction mixture in the reaction zone, assuming the rnols ofproduct mixture are equivalent to the rnols of feed mixture. For thepurpose of calculation of residence times, the reaction zone is theportion of the reactor containing catalyst.

The catalytic surface described is the surface which is exposed in thedehydrogenation zone to the reactor, that is, if a catalyst carrier isused, the composition described as a catalyst refers to the compositionof the surface and not to the total composition of the surface coatingplus carrier. Catalyst binding agents or fillers may be used, but thesewill not ordinarily exceed about 50 percent or 60 percent by weight ofthe catalytic surface. These binding agents and fillers will preferablybe essentially inert. The quantity of catalyst utilized will bedependent upon such variables as the temperature of reaction, theconcentration of oxygen, the age of the catalyst, and the flow rates ofthe reactants. The catalyst will by definition be present in a catalyticamount and generally the nickel ferrite together with any nickel andiron atoms not combined as nickel ferrite will be the main activeconstituents. The amount of catalyst Will ordinarily be present in anamount greater than 10 square feet of catalyst surface per cubic foot ofreaction zone containing catalyst. Of course, the amount of catalyst maybe much greater, particularly when irregular surface catalysts are used.When the catalyst is in the form of particles, either supported orunsupported, the amount of catalyst surface may be expressed in terms ofthe surface area per unit weight of any particular volume of catalystparticles. The ratio of catalytic surface to weight will be dependentupon various factors, including the particle size, particle sizedistribution, apparent bulk density of the particles, amount of activecatalyst coated on the carrier, density of the carrier, and so forth.Typical values for the surface to weight ratio are such as aboutone-half to 200 square meters per gram, although higher and lower valuesmay be used.

The dehydrogenation reactor may be of the fixed bed or fluid bed type.Conventional reactors for the production of unsaturated hydrocarbons aresatisfactory. Excellent results have been obtained by packing thereactor with catalyst particles as the method of introducing thecatalytic surface. The catalytic surface may be introduced as such or itmay be deposited on a carrier by methods known in the art such as bypreparing an aqueous solution or dispersion of a catalytic material andmixing the carrier with the solution or dispersion until the activeingredients are coated on the carrier. If a carrier is utilized, veryuseful carriers are silicon carbide, pumice and the like. When carriersare used, the amount of catalyst on the carrier will generally bebetween about 5 to weight percent of the total weight of the activecatalytic material plus carrier. Another method for in troducing therequired surface is to utilize as a reactor a small diameter tubewherein the tube wall is catalytic or is coated with catalytic material.Other methods may be utilized to introduce the catalytic surface such asby the use of rods, wires, mesh, or shreds and the like of catalyticmaterial.

According to this invention, the catalyst is autoregenerative and theprocess is continuous. Moreover, small amounts of tars and polymers areformed as compared to some prior art processes.

In the following examples will be found specific embodiments of theinvention and details employed in the practice of the invention. Percentconversion refers to the mols of hydrocarbon consumed per 100 mols ofhydrocarbon fed to the reactor, percent selectively refers to the molsof product formed per 100 mols of hydrocarbon consumed, and percentyield refers to the mols of product formed per mol of hydrocarbon fed.

EXAMPLE 1 A nickel ferrite catalyst was prepared from 37.4 grams ofnickelous oxide, 79.9 grams ferric oxide and 74.6 grams of potassiumchloride. The dry ingredients were mixed thoroughly and then reacted at900 C. for a period of 1% hours. After cooling to room temperature,hot'distilled water was used to extract the potassium chloride from thereacted mixture. A highly magnetic dark brown solid was obtained afterthe reaction mixture was dried in an oven at 110 C. The product wasfound to be nickel ferrite by X-ray diffraction analysis.-

The nickel ferrite was coated on 4 to 5 mesh alumina supports(Carborundum Company type AMC). Butene- 2 was dehydrogenated atatmospheric pressure in a Vycor glass reactor (36 x 1" OD.) having a 35cc. catalyst bed. The remainder of the reactor was filled with x 1A"Vycor Raschig rings. Butene-Z, oxygen, and steam were introduced into anadapter located on top of the glass reactor, and the efiluent gases werepassed through a cold water condenser to remove most of the steam.Samples of the eflluent gases were withdrawn with a syringe at the exitfrom the condenser. They were analyzed in a vapor chromatograph. Thetemperature inside the reactor was measured by a type J ironconstantanthermocouple enclosed in a 7 mm. O.D. Vycor tubing thermocouple well.The oxygen was fed as C.P. oxygen, 99.5 mol percent minimum oxygen.

The butene-2, oxygen and steam was fed to the reactor in an amount of0.6 mol of oxygen per mol of butene-2 and mols of steam per mol ofbutene-2. The liquid hourly space velocity was 1.0 (with the calculationbeing based on the volume of the reactor containing catalyst, that is,the cc. catalyst section). At a maximum temperature in the reactor of470 C., the yield of butadiene-1,3 was 64 mol percent per pass.

An X-ray diffraction pattern was obtained on the catalyst of Example 1.The powder pattern was obtained using a Norelco constant potentialdiffraction unit, type number 12045, equipped with a wide rangegoniometer type No. 42202, chromium tube type No. 32116, Geiger countertype No. 34473; all coupled to the Norelco circuit panel-type No. 12049.The chromium K alpha radiation was supplied by operating the tube at aconstant potential of kilovolts and a current of 10 milliamperes. Avanadium filter was used to remove K beta radiation. The Geiger tubedetector was operated at 1575 volts. A 1 divergence, 0.006 inchreceiving, and 1 scatter slits were used. Strip chart recordings usedfor identification were made with a scanning speed of 1 2 theta perminute with a chart speed of one-half inch per minute. A time constantof 2 seconds and a full scale chart reading of 100 counts per second wasused. Under the above conditions, the patterns noted below were found.

1 Vycor is the trade name of Corning Glass Works, Corning, N.Y., and iscomposed of approximately 96 percent silica with the remaining beingessentially B203.

The values of I/I noted are those for NiFe O A small amount of aFe O wasfound in the patterns. The data is reported in the table.

Table d: UL 4.82 14 2.698 weak 1.453 weak 1.31s 4 EXAMPLE 2 The generalprocedure of Example 1 was repeated with the exception that potassiumchloride was not used in the formation of the nickel ferrite. The yieldof butadiene 1,3 was 63 mol percent.

EXAMPLE 3 A nickel ferrite catalyst was prepared from nickel carbonateand hydrated yellow ferric iron oxide. The ratio of ingredients was suchthat there were two atoms of iron per atom of nickel. The nickelcarbonate and iron oxide were thoroughly mixed in an aqueous slurry andthe slurry thereafter was dried. The dry cake was broken into lumps anda 4 to 8 mesh fraetionwas reacted for 30 minutes at 950 C. to form thenickel ferrite. The catalyst was evaluated for the dehydrogenation ofbutene-2 to butadiene-1,3. A stainless steel reactor one inch indiameter was used and 20 cc. of the 4 to 8 mesh catalyst was utilized.30 mols of steam and 0.6 mol of O (fed as air) were fed per mol ofbutene-2. The flow rate of butene-2 was 1.0 LHSV. At a reactortemperature of 400 C., the selectivity to butadiene was greater than molpercent of the butene consumed.

EXAMPLE 4 Example 3 was repeated with the exception that the catalystcontained 2.5 atoms of iron per atom of nickel. At a reactor temperatureof 400 C., the conversion was 64 percent and the selectivity tobutadiene was 93 percent.

EXAMPLE 5 Example 3 was repeated with the exception that the catalystcontained 1.67 atoms of iron per atom of nickel and the amount of oxygenused was increased to 0.75 mol of 0 per mol of butene-2 fed. At areactor temperature of 400 C., the selectivity to butadiene-1,3 was 86percent.

EXAMPLE 6 The, procedure of Example 1 was repeated using the catalyst ofExample 1. Additionally, 0.03 mol of bromine (fed as an aqueous solutionof HBr) per mol of butene was fed to the reactor. Oxygen was fed at arate of 0.85 mol of 0 per mol of butene and steam was employed in aratio of 20 mols of steam per mol of butene fed. The flow rate of butenewas 0.6 LHSV. At a reactor temperature of 550 C., the yield of butadienewas 74 mol percent per pass.

When an equivalent amount of iodine and chlorine were substituted forthe bromine in Example 6, excellent yields of butadiene-1,3 wereobtained.

The catalysts are not limited to those illustrated in the examples.Other methods of preparation and other compositions may be employed. Theatoms of iron will preferably be present in an amount from about 20 to95 weight percent, based on the total weight of the atoms of iron andnickel in the catalyst surface, but generally will be between 40 and 90and a preferred ratio is from 50 to 85 weight percent iron. Particularlypreferred are catalysts having a weight percent of iron from or about 55to 81 percent by weight iron based on the total weight of atoms of ironand nickel. Valuable catalysts were produced comprising as the mainactive consti-tutents iron, nickel and oxygen in the catalytic surfaceexposed to the reaction gases. High yields of product are obtained withcatalysts having iron as the predominant metal in the catalytic surface.Preferably at least about 50 and generally at least about 65 weightpercent of the atoms of nickel and iron will be present as nickelferrite. Included in the definition of ferrites are the activeintermediate oxides. The preferred nickel ferrite has a cubicface-centered crystal structure. Ordinarily the nickel ferrite will notbe present in the most highly oriented crystalline structure, because ithas been found that superior results may be obtained with catalystswherein the nickel ferrite is relatively disordered, that is where thereare defects in the crystalline structure. The desired catalyst may beobtained by conducting the reaction to form the active catalyst atrelatively low temperatures, that is, at temperatures lower than some ofthe very high temperatures used for the formation of nickel ferriteprepared for semiconductor applications. Generally the temperature ofreaction for the formation of the catalyst comprising nickel ferritewill be less than 1300 C. and preferably less than 1150 C. Of course,under certain conditions momentary temperatures above these temperaturesmight also be permissible. The reaction time at the elevated temperaturein the formation of the catalyst may preferably be from about fiveminutes to four hours at elevated temperatures high enough to causeformation of nickel ferrite but less than about 1150 C. Any iron notpresent in the form of nickel ferrite will desirably be presentpredominantly as gamma iron oxide. The alpha iron oxide will preferablybe present in an amount of no greater than 40 weight percent of thecatalytic surface, such as no greater than about 30 weight percent.

Although excellent results are obtained with the catalysts of thisinvention with a feed containing only the hydrocarbon, oxygen andperhaps steam or a diluent, it is one of the advantages of thisinvention that halogen may also be added to the reaction gases to giveexcellent results. The addition of halogen to the feed is particularlyeffective when the hydrocarbon to be dehydrogenated is saturated.

The source of halogen fed to the dehydrogenation zone may be eitherelemental halogen or any compound of halogen which would liberatehalogen under the conditions of reaction. Suitable sources of halogenare such as hydrogen iodide, hydrogen bromide and hydrogen chloride;aliphatic halides such as ethyl iodide, methyl bromide, 1,2-dibromoethane, ethyl bromide, amyl bromide and allyl bromide; cycloaliphatichalides such as cyolohexylbromide; aromatic halides such as benzylbromide; halohydrins such as ethylene bromohydrin; halogen substitutedaliphatic acids such as bromoacetic acid; ammonium iodide; ammoniumbromide; ammonium chloride; organic amine halide salts such as methylamine hydrobromide; and the like. Mixtures of various sources of halogenmay be used. The preferred sources of halogen are iodine, bromine andchlorine and compounds thereof such as hydrogen bromide, hydrogeniodide, hydrogen chloride, ammonium bromide, ammonium iodide, ammoniumchloride, alkyl halides of one to six carbon atoms and mixtures thereof,with the iodine and bromine compounds being particularly preferred, andthe best results having been obtained with ammonium iodide, bromide orchloride. When terms such as halogen liberating materials or halogenmaterials are used in the specification and claims, this includes anysource of halogen such as elemental halogens, hydrogen halides orammonium halides. The amount of halogen, calculated as elementalhalogen, may be as little as about 0.0001 or less mol of halogen per molof the hydrocarbon compound to be dehydrogenated to as high as 0.2 or0.5

or higher. The preferred range is from about 0.001 to 0.09 mol ofhalogen per mol of the hydrocarbon to be dehydrogenated.

Improved catalysts may be obtained by reducing the catalyst of theinvention. The reduction of the catalyst may be accomplished prior tothe initial dehydrogenation, or the catalyst may be reduced after thecatalyst has been used. It has been found that a used catalyst may beregenerated by reduction and, thus, even longer catalyst life obtained.The reduction may be accomplished with any gas which is capable ofreducing iron oxide to a lower valence such as hydrogen, carbon monoxideor hydrocarbons. Generally the flow of oxygen will be stopped during thereduction step. The temperature of reduction may be varied but theprocess is most economical at temperatures of at least about 200 C.,with the upper limit being about 750 C. or 900 C. or even higher undercertain conditions.

The preferred catalyst surface will generally have X- ray diffractionpeaks at d spacings within or about 4.79 to 4.85, 2.92 to 2.98, 2.48 to2.54, 2.05 to 2.11, 1.57 to 1.63, and 1.44 to 1.49, with the mostintense peak being between 2.48 to 2.54. Particularly preferredcatalysts will have d spacings within or about 4.80 to 4.84, 2.93 to2.97, 2.50 to 2.53, 2.07 to 2.10, 1.59 to 1.61, and 1.46 to 1.49, withthe most intense peak falling within or about 2.50 to 2.53. These X-raydeterminations are suitably run with a cobalt tube.

We claim:

1. A process for the dehydrogenation of hydrocarbons having at leastfour carbon atoms which comprises contacting in the vapor phase at atemperature of greater than 250 C. a mixture of the said hydrocarbon tobe dehydrogenated and from 0.2 to 2.5 mols of oxygen per mol of the saidhydrocarbon with a catalyst for the dehydrogenation comprising nickeland iron wherein the atoms of iron are present in an amount of about 20to weight percent based on the total weight of the atoms of iron andnickel, to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon.

2. A process for the dehydrogenation of hydrocarbons having at leastfour carbon atoms which comprises contacting in the vapor phase at atemperature of greater than 250 C. a mixture of the said hydrocarbon tobe dehydrogenated and from 0.2 to 2.5 mols of oxygen per mol of the saidhydrocarbon with a catalyst for the dehydrogenation comprising nickelferrite to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon.

3. A process for the dehydrogenation of hydrocarbons having from 4 to 5carbon atoms which comprises contacting in the vapor phase at atemperature of greater than 250 C. a mixture of the said hydrocarbon tobe dehydrogenated and from 0.2 to 2.5 mols of oxygen per mol of the saidhydrocarbon with a catalyst for the dehydrogenation comprising nickelferrite wherein the atoms of iron are present in an amount of about 40to 90 weight percent based on the total weight of the atoms of iron andnickel, to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon, the initial partialpressure of the said hydrocarbon being equivalent to less than one-halfatmosphere at a total pressure of one atmosphere.

4. A process for the dehydrogenation of a hydrocarbon selected from thegroup consisting of n-butene, n-butane and mixtures thereof whichcomprises contacting in the vapor phase at a temperature of greater thanabout 325 C. a mixture of the said hydrocarbon to be dehydrogenated andfrom about 0.25 to about 1.6 mols of oxygen per mol of the saidhydrocarbon with a catalyst for the dehydrogenation comprising nickelferrite to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon, the initial partialpressure of the said hydrocanbon being equivalent to less than one-halfatmosphere at a total pressure of one atmosphere.

5. A process for the dehydrogenation of aliphatic hydrocarbons having atleast four carbon atoms which comprises contacting in the vapor phase ata temperature of from about 325 C. to 525 C. a mixture of the saidhydrocarbon to be dehydrogenated and from 0.2 to 1.6 mols of oxygen permol of the said hydrocarbon with a catalyst for the dehydrogenationcomprising nickel and iron wherein the atoms of iron are present in anamount of 50 to 85 weight percent based on the total weight of the atomsof iron and nickel, to produce a dehydrogenated hydrocarbon producthaving the same number of carbon atoms as the said hydrocarbon, theinitial partial pressure of the said hydrocarbon being equivalent toless than onehalf atmosphere at a total pressure of one atmosphere.

6. A process for the dehydrogenation of aliphatic hydrocarbons having atleast four carbon atoms which comprises contacting in the vapor phase ata temperature of greater than 325 C. a mixture of the said hydrocarbonto be dehydrogenated from 0.2 to 2.5 mols of oxygen per mol of the saidhydrocarbon and from 2 to 40 mols of steam per mol of the saidhydrocarbon with a catalyst for the dehydrogenation comprising nickelferrite to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon.

7. A process for the dehydrogenation of aliphatic hydrocarbons having atleast four carbon atoms which comprises contacting in the vapor phase ata temperature of greater than 325 C. a mixture of the said hydrocarbonto be dehydrogenated and from 0.2 to 2.5 mols of oxygen per mol of thesaid hydrocarbon with an autoregenerative catalyst for thedehydrogenation comprising nickel and iron wherein the atoms of iron arepresent in an amount of 55 to 81 weight percent based on the totalweight of the atoms of iron and nickel, to produce a dehydrogenatedhydrocarbon product having the same number of carbon atoms as the saidhydrocarbon, the initial partial pressure of the said hydrocarbon beingequivalent to less than one-half atmosphere at a total pressure of oneatmosphere.

8. A process for the dehydrogenation of hydrocarbons having from 4 to 5carbon atoms which comprises contacting in the vapor phase at atemperature of at least about 375 C. a mixture of the said hydrocarbonto be dehydrogenated and from 0.35 to 1.2 mols of oxygen per mol of thesaid hydrocarbon with a catalyst for the dehydrogenation comprisingnickel ferrite wherein the atoms of iron are present in an amount of 55to 81 weight percent based on the total weight of the atoms of iron andnickel, to produce a dehydrogenated hydrocarbon product having the samenumber of carbon atoms as the said hydrocarbon, the initial partialpressure of the said hydrocarbon being equivalent to less than one-thirdatmosphere at a total pressure of one atmosphere.

9. A process for the dehydrogenation of a hydrocarbon selected from thegroup consisting of n-butene, n-butane and mixtures thereof whichcomprises contacting in the vapor phase at a temperature of from 375 C.to 525 C. and at a pressure of 4 p.s.i.a. to 125 p.s.i.a. a mixture ofthe said hydrocarbon to be dehydrogenated and from about 0.25 to about1.6 mols of oxygen per mol of the said hydrocarbon with a catalyst forthe dehydrogenation comprising nickel ferrite to produce adehydrogenated hydrocarbon product having the same number of carbonatoms as the said hydrocarbon, the initial partial pressure of the saidhydrocarbon being equivalent to less than one-fifth atmosphere at atotal pressure of one atmosphere.

10. A process for the dehydrogenation of butene to butadiene-l,3 whichcomprises contacting in the vapor phase at a temperature of from 375 C.to 575 C. and at a total pressure of less than 75 p.s.i.a. a mixture ofthe said butene, from 8 to about 35 mols of steam and from 0.35 to 1.2mols of oxygen per mol of the said butene with a catalyst for thedehydrogenation comprising nickel ferrite wherein the atoms of iron arepresent in an amount of 55 to 81 weight percent based on the totalweight of the atoms of iron and nickel, to produce butadiene-1,3.

11. A process for the vapor phase dehydrogenation of aliphatichydrocarbons having at least four carbon atoms which comprisescontacting in the vapor phase at a temperature of greater than 250 C. amixture of the said hydrocarbon to be dehydrogenated, from 0.2 to 2.5mols of oxygen per mol of the said hydrocarbon and a halogen with acatalyst for the dehydrogenation comprising nickel ferrite wherein theatoms of iron are present in an amount of about 40 to weight percentbased on the total weight of the atoms of iron and nickel, to produce adehydrogenated hydrocarbon product having the same number of carbonatoms as the said hydrocarbon, the initial partial pressure of the saidhydrocarbon being equivalent to less than one-half atmosphere at a totalpressure of one atmosphere.

12. A process for the dehydrogenation of aliphatic hydrocarbons havingfrom 4 to 5 carbon atoms which comprises contacting in the vapor phaseat a temperature of greater than 325 C. a mixture of the saidhydrocarbon to be dehydrogenated, from 0.25 to 1.6 mols of oxygen permol of the said hydrocarbon and from 0.0001 to 0.2 mols of halogen permol of the said hydrocarbon with an autoregenerative catalyst for thedehydrogenation comp-rising nickel ferrite wherein the atoms of iron arepresent in an amount of about 40 to 90 weight percent based on the totalweight of the atoms of iron and nickel, to produce a dehydrogenatedhydrocarbon product having the same number of carbon atoms as the saidhydrocarbon, the initial partial pressure of the said hydrocarbon beingequivalent to less than one-half atmosphere at a total pressure of oneatmosphere.

13. A process for the dehydrogenation of aliphatic hydrocarbons havingfrom 4 to 5 carbon atoms which comprises contacting in the vapor phaseat a temperature of greater than 325 C. a mixture of the saidbydrocarbon to be dehydrogenated, from 0.25 to 1.6 mols of oxygen permol of the said hydrocarbon with an autoregenerative catalyst for thedehydrogenation comprising nickel ferrite wherein the atoms of iron arepresent in an amount of about 40 to 90 weight percent based on the totalweight of the atoms of iron and nickel, to produce a dehydrogenatedhydrocarbon product having the same number of carbon atoms as the saidhydrocarbon, the initial partial pressure of the said hydrocarbon beingequivalent to less than one-half atmosphere at a total pressure of oneatmosphere.

14. A process for the dehydrogenation of butene to butadiene-l,3 whichcomprises feeding to a reactor in the vapor phase at a temperature of atleast 250 C. a gaseous mixture of the said butene and from 0.35 to 1.2mols of oxygen per mol of the said butene with an autoregenerativecatalyst for the dehydrogenation comprising nickel and iron wherein theatoms of iron are present in an amount of about 2 atoms of iron per atomof nickel based on the total weight of the atoms of iron and nickel, toproduce butadiene-l,3, the initial partial pressure of the said butenebeing equivalent to less than one-fifth atmosphere at a total pressureof one atmosphere.

15. A process for the dehydrogenation of aliphatic hydrocarbons havingat least four carbon atoms which comprises contacting in the vapor phaseat a temperature of greater than 250 C. a mixture of the saidhydrocarbon to be dehydrogenated and from 0.2 to 2.5 mols of oxygen permol of the said hydrocarbon with a catalyst for the dehydrogenationcomprising nickel ferrite to produce a dehydrogenated hydrocarbonproduct having the same number of carbon atoms as the said hydrocarbon,the initial partial pressure of the said hydrocarbon being equivalent toless than one-half atmosphere at a total pressure of one atmosphere,said catalyst having been reduced with a reducing gas.

16. A process for the preparation of butadiene-1,3 which comprisescontacting in the vapor phase at a temperature of 375 C. to 525 C. andat a total pressure of about 4 p.s.i.a. to 100 p.s.i.a. a mixture ofn-butene and from 0.35 to 1.2 mols of oxygen and from 8 to 35 mols ofsteam per mol of the said n-butene with an autoregenerative catalyst forthe dehydrogenation comprising nickel ferrite wherein the atoms of ironare present in amount of 55 to 81 weight percent based on the totalweight of the atoms of iron and nickel with any iron not present in theform of nickel ferrite being predominantly present as gamma iron oxideto produce butadicue-1,3.

17. A process for the preparation of butadiene-1,3 which com-prisescontacting in the vapor phase at a temperature of 37 5" C. to 525 C. andat a total pressure of about 4 p.s.i.a. to 100 p.s.i.a. a mixture ofn-butene and from 0.35 to 1.2 mols of oxygen and from 8 to 35 mols ofsteam per mol of the said n butene with an autoregenerative catalyst forthe dehydrogenation comprising nickel ferrite wherein the atoms of ironare present in an amount of to 81 weight percent based on the totalweight of the atoms of iron and nickel with any iron not present in theform of nickel ferrite being predominantly present as gamma iron oxideto produce butadiene- 1,3, and after the yield of butadiene-1,3 hasfallen off after continued use regenerating the catalyst by reducing thecatalyst with hydrogen.

References Cited by the Examiner UNITED STATES PATENTS 3,168,587 2/1965Michaels et a1. 260--683.3 3,179,707 4/1965 Lee 260-669 3,207,811 9/1965Bajars 26068O DELBERT E. GANTZ, Primary Examiner.

G. E. SCHMITKONS, Assistant Examiner.

1. A PROCESS FOR THE DEHYDROGENATION OF HYDROCARBONS HAVING AT LEASTFOUR CARBON ATOMS WHICH COMPRISES CONTACTING IN THE VAPOR PHASE AT ATEMPERATURE OF GREATER THAN 250*C. A MIXTURE OF THE SAID HYDROCARBONS TOBE DEHYDROGENATED AND FROM 0.2 TO 2.5 MOLS OF OXYGEN PER MOL OF THE SAIDHYDROCARBON WITH A CATALYST FOR THE DEHYDROGENATION COMPRISING NICKELAND IRON WHEREIN THE ATOMS OF ION ARE PRESENT IN AN AMOUNT OF ABOUT 20TO 90 WEIGHT PERCENT BASED ON THE TOTAL WEIGHT OF THE ATOMS OF ION ANDNICKEL, TO PRODUCE A DEHYDROGENATED HYDROCARBON PRODUCT HAVING THE SAMENUMBER OF CARBON ATOMS AS THE SAID HYDROCARBON.